Flagstaff Scientist Reflects on Cassini Spacecraft’s Final Days

Sep 14, 2017

The Cassini spacecraft mission ends tomorrow after two decades in space. A Flagstaff scientist on the mission team says Cassini transformed our knowledge of Saturn and especially its strange moon Titan. KNAU’s Melissa Sevigny spoke with Randy Kirk of the U.S. Geological Survey from Pasadena, California, where the team has gathered to witness the spacecraft’s final moments.

A Cassini photograph of the moon Titan behind Saturn's rings
Credit NASA/JPL/Space Science Institute

Randy, tell me what the scene is like out in Pasadena with all the scientists gathered at the Jet Propulsion Laboratory to witness Cassini’s final moments. How is everybody feeling?

Well, obviously it’s bittersweet. We’re sad to see the mission come to an end, not just because the science is coming to an end for now, but because we’ve been a family professionally for decades now. On the other hand we’ve learned so much and the mission’s been so successful that we really can celebrate that, and people are doing so, and we believe in a future for studies of the Saturn system. There’s so much that we’ve learned that says that we have to go back there and do another mission or missions. 

When did you first get involved with the Cassini mission?

I was one of the initial applicants to be on the radar instrument that is dedicated to mapping Titan,  and that was a proposal I wrote in 1990 when I was only out of grad school for a couple of years. 

I think there’s been a lot of excitement about the information Cassini has sent back not just about Saturn but actually about those moons, moons like Titan and Enceladus. Can you tell me some of the most interesting things we’ve found out?

Sure. What’s cool about Titan was, we knew it was unusual before we went there, we knew it was a big, we knew it had an atmosphere, but what we’ve seen is a world that in many ways is more like Earth than anything else in the solar system. It’s doing many of the same things, it’s active today. But it’s doing it with completely different materials. And there is rain and rivers and lakes and seas, but they’re made up of what we would call liquefied natural gas.   

We knew there were these organic molecules like natural gas on Titan before we went there but we really didn’t know what they would be doing. So we flew past Titan several times, saw only dry land, and then finally we flew over the North Pole of Titan and we saw a land of hundreds of lakes.

That was the probably the most exciting moment in the mission, just to know finally what those reservoirs of liquid were and that they were part of a whole system that was carving rivers and eroding mountains, and so on, and how similar it is in some ways to the Earth.  

Is you were able to pick a place in the solar system to go next, to send another spacecraft to, what would it be?

That’s easy, Titan! Titan is so complex, and so tantalizing, and could be an abode for a type of life totally different than anything we have on Earth, that it just floats to the top of the list. It is not a place I would ever want to go personally. Aside from being about minus 400 degrees Fahrenheit, the atmosphere is full of small amounts of what Earthlings would consider extremely toxic chemicals. So it’s not going to be a fun place to vacation, ever.

Thanks so much for speaking with me, I really appreciate it.

My pleasure.

That was Randy Kirk with the U.S. Geological Survey in Flagstaff speaking with us from Pasadena, California. Cassini will crash into Saturn’s atmosphere and burn up early tomorrow morning.